The present invention relates to a method of forming a pattern using an organosilicon film pattern as an etching mask.
The manufacturing method of a semiconductor device generally involves the steps of depositing a plurality of materials on a semiconductor wafer, and patterning these deposited films into a desired pattern. This patterning step is generally performed by the steps of depositing a photosensitive material called a resist on a work film (a film to be worked or processed) formed on the surface of the wafer thereby forming a resist film, selectively exposing this resist film to a patterning light using as a light source ultraviolet rays, and then developing the resist film.
It is important in this patterning process to prevent a reflection of the patterning light from the work film of the wafer. In order to solve this problem, Japanese Patent Unexamined Publication S/49-55280 describes a method of forming an antireflection film between a resist film and a work film. In this case, various materials may be employed as the antireflection film. However, in view of the possibility to utilize a spin-coating method which enables to save the process cost, the following materials are mainly employed.
(1) A material comprising a spin glass added with a dye (Jpn. J. Appl. Phys. Vol. 35 (1996) pp. L1257-L1259: PA1 (2) A plasma-decomposition type resin such as polysulfone (Japanese Patent Unexamined Publication S/59-93448): and PA1 (3) Polysilane (U.S. Pat. No. 5,401,614). PA1 forming an organosilicon film on a work film, the organosilicon film comprising an organosilicon compound having a silicon-silicon bond in a backbone chain thereof and a glass transition temperature of 0.degree. C. or more; PA1 forming a resist pattern on the organosilicon film; and PA1 transcribing the resist pattern on the organosilicon film through an etching of the organosilicon film by making use of an etching gas comprising a gas containing at least one kind of atom selected from the group consisting of chlorine, bromine and iodine. PA1 forming an organosilicon film on a work film, the organosilicon film containing an organosilicon compound having a silicon-silicon bond in a backbone chain thereof and a glass transition temperature of 0.degree. C. or more; PA1 forming a resist pattern on the organosilicon film; and PA1 etching the organosilicon film by making use of an etching gas comprising a gas containing at least one kind of atom selected from the group consisting of chlorine, bromine and iodine; PA1 oxidizing the organosilicon film; and PA1 etching the work film by making use of a pattern comprising the oxidized organosilicon film as an etching mask. PA1 forming an organosilicon film on a work film, the organosilicon film comprising an organosilicon compound having a silicon-silicon bond in a backbone chain thereof and a glass transition temperature of 0.degree. C. or more; PA1 forming a resist pattern on the organosilicon film; PA1 etching the organosilicon film by making use of an etching gas comprising a gas containing at least one kind of atom selected from the group consisting of chlorine, bromine and iodine; PA1 etching the work film by making use of a pattern comprising the organosilicon film as an etching mask; and PA1 removing the pattern of the organosilicon film by making use of a mixture of a gas containing oxygen atom and a gas containing at least one kind of atom selected from the group consisting of chlorine, bromine and fluorine.
The employment of the material of (1) is accompanied with problems that when a chemical amplification type resist having a high resolution is employed, it is difficult to obtain an excellent resist profile, i.e. resulting in a resist profile exhibiting a footing or undercut of resist. The employment of the material of (2) is also accompanied with problems at the occasion of transcribing a resist pattern by making use of a dry etching method that since the etching rate of the antireflection film is almost identical with that of the resist, a resist pattern may be entirely lost during the etching of the antireflection film, thus making it difficult to work to obtain the antireflection film of desired dimension. In particular, when the film thickness of the resist is thinned to the same degree as that of the antireflection film with a view to enhance the resolution, this problem would become more serious.
On the other hand, the employment of the material (3) may sometimes cause a denaturing of the polysilane film at the occasion of transcribing a resist pattern by making use of a dry etching method thereby making it difficult to precisely perform the etching the polysilane film. Moreover, there is another problem that if etching of this polysilane film is performed by making use of a halogen type gas, the resist pattern may become thickened by a deposition material so that it is impossible to perform the etching with high dimensional control.